Ultraviolet Damage Resistance of Laser Coatings

The damage resistance of several thin-film materials used in ultraviolet laser optics was measured at 266 nm and 355 nm. The coatings included single, quarter-wave (QW) layers of NaF, LaF3, MgF2, Tho2, AI2O3, HfO2, ZrO2, Y2O3 and SiO2, plus multilayer reflectors composed of some of these materials. The substrates were uv-grade fused silica. Single-shot thresholds were obtained with 22-ns and 27-ns (FWHM) pulses at 266 and 355 nm, respectively. One of the samples had previously been tested using 20-ps pulses, providing a pulsewidth comparison.